Floating collars are used to seal the fuel nozzles that are mounted in openings within an engine combustor wall in a gas turbine engine. The fuel nozzles protrude through the floating collar which is mounted in an opening in the combustor wall to accommodate relative movement necessary to deal with thermal expansion and contraction. In most prior art designs, the combustor is a relative thin sheet metal walled structure supported within a plenum filled with compressed air. The compressed air typically enters the combustor through various openings in the nozzle to create a swirling effect and through openings in the combustor to create cooling film and mix with the fuel aerosol sprayed within the combustor.
Fuel nozzles may be mounted at the inward ends of cantilevered fuel tubes where fuel tubes are individually fixed to an engine core structure and are supplied with liquid fuel via an external fuel supply manifold. Alternatively, fuel nozzles may extend into contact with the combustor from an internal fuel supply manifold assembly. To accommodate relative axial and radial motion between the nozzle and the combustor due to thermal expansion and contraction and to control the flow of air from the plenum into the combustor, floating collars have been used in the prior art. A disadvantage of prior art floating collars is that complex anti-rotation devices are often necessary to prevent the rotation of the floating collar due to swirling airflows and vibration. Continued rotation would quickly wear away the nozzle surface and is prevented by locking devices that permit some radial or axial motion to accommodate thermal expansion and contraction while preventing rotation.
Conventional collars are also subject to vibration fretting of the combustor wall due to significant vibration since the nozzles are often supported on the ends of slender cantilevered fuel tubes anchored at a distance from the nozzle to the engine core structure.
U.S. Pat. No. 4,322,945 to Peterson et al. discloses a conventional fuel nozzle heat shield with anti-rotation device included.
U.S. Pat. No. 4,454,711 to Ben-Porat discloses another example of means to accommodate relative motion between the nozzle and supply fuel tube and the combustor. In the case of Ben-Porat, a spherical ball end socket joint is provided with spring loaded mount in a relatively complex assembly.
It is an object of the present invention to mechanically dampen vibration between the fuel nozzle and combustor by providing friction both axially and radially between the nozzle and combustor.
It is a further object of the invention to prevent generation of high vibratory stresses through mechanically dampening vibration between the nozzles and combustor.
Further objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below.